This invention relates to improved apparatus and methods for the treatment of prostate cancer. More particularly, the present invention provides improved methods and apparatus for administering brachytherapy.
Excluding nonmelanoma skin cancers, prostate cancer is the most common cancer afflicting American men. The American Cancer Society estimates that over 180,00 new cases will be diagnosed in the U.S. in the year 2000 alone, and that nearly 32,000 people will die from the disease. Prostate cancer is second only to lung cancer as the leading cause of cancer death in men, accounting for roughly 11%.
Prostate cancer is defined as malignant tumor growth within the prostate gland. Its cause is unknown, although high dietary fat intake and increased testosterone levels are believed to be contributory factors. A letter scale (xe2x80x9cAxe2x80x9d through xe2x80x9cDxe2x80x9d), which accounts for the location of the cancer, is commonly used to classify the stage of disease. In Stage A, the tumor is not palpable but is detectable in microscopic biopsy. Stage B is characterized by a palpable tumor confined to the prostate. By Stage C, the tumor extends locally beyond the prostate with no distant metastasis. By Stage D, cancer has spread to the regional lymph nodes or has produced distant metastasis.
In the early stages, prostate cancer is most commonly treated by prostate removal or by brachytherapy. More advanced cases are treated by hormonal manipulation or orchiectomy to reduce testosterone levels and curb spreading of the disease, by chemotherapy, or by external beam radiation therapy.
With regard to treatment of early stage prostate cancer, the state of the art has several drawbacks. Radical prostatectomy is often recommended for treatment of localized stage A and B prostate cancers. Under general or spinal anesthesia, an incision is made through a patient""s abdomen or perineal area, and the diseased prostate is removed. The procedure is lengthy, especially if a lymph node dissection is simultaneously performed, and requires a hospital stay of 2-5 days. Possible complications include impotence and urinary incontinence.
Internal radiation therapy or brachytherapy has recently been modified and holds great promise for the treatment of early stage prostate cancer. Radioactive pellets or seeds of, for example, iodine-125, gold-198, palladium-103, ytterbium-169, or iridium-192, are deposited directly into the prostate through needle placement. Imaging tests, such as transrectal ultrasound, CT scans, or MRI, are used to accurately guide placement of the radioactive material. Advantageously, radiation is administered directly to the prostate with less damage to surrounding tissues, requiring a significantly smaller radiation dosage as compared to external beam radiation therapy. Furthermore, the procedure need only be performed once. Complications include a lower, yet still significant, incidence of impotence and urinary incontinence, compared to prostate removal procedures.
The radioactive seeds are placed inside thin needles, which are inserted through the skin of the perineum (area between the scrotum and anus) into the prostate. U.S. Pat. No. 5,928,130 to Schmidt provides a slightly modified example of such a needle device. Each needle is slowly retracted with a spinning motion by a first practitioner while a plunger within the needle, and proximal of the radioactive seeds, is held stationary by a second practitioner. The plunger keeps the seeds in place during retraction of the needle, while rotation of the needle during retraction prevents jamming of the seeds while delivering the seeds in a line within the prostate.
The seeds, which are permanently implanted, give off radiation for weeks or months. Their presence causes little discomfort, and they are left in the prostate after decay of the radioactivity. For about a week following needle insertion, patients may experience pain in the perineal area, and urine may have a red-brown discoloration.
Although, when performed correctly, radioactive seed implantation may provide several benefits, compared to prostate removal and other techniques, current surgical apparatus and methods for delivering the seeds to target locations within the prostate are somewhat crude and are subject to practitioner error. The procedure requires two practitioners working cooperatively to deliver the seeds. The depth to which the plunger is inserted into the needle, in the loaded and advanced states, is critical but crudely measured. The plunger and needle may accidentally move relative to one another during needle insertion or seed delivery, causing improper positioning of deposited seeds. The needle is somewhat flexible and should be inserted quickly to minimize bending at its distal tip, but this is often not done due to inexperience or technical ability of the practitioners, or to avoid potential relative movement between the plunger and the needle.
Attempts have been made to address various aspects of these concerns. For example, U.S. Pat. No. 4,815,449 to Horowitz describes an absorbable member with seeds spaced within the member to facilitate proper spacing during delivery. U.S. Pat. No. 4,700,692 to Baumgartner describes apparatus for delivering all of the seeds simultaneously. PCT document WO 99/20337 to Rydell describes a gun-like apparatus for delivering seeds once the needle has been inserted into the prostate.
While each of these devices may provide some benefit over the prior art, none satisfactorily addresses the shortcomings of current techniques. In view of the drawbacks associated with previously-known methods and apparatus for brachytherapy, it would be desirable to provide methods and apparatus that overcome such drawbacks.
It further would be desirable to provide methods and apparatus that allow efficient preparation of the apparatus for therapeutic administration.
It still further would be desirable to provide methods and apparatus for administering brachytherapy that require only one medical practitioner.
It further would be desirable to provide methods and apparatus that yield easy measurement and maintenance of plunger depth within the needle.
It would also be desirable to provide methods and apparatus for brachytherapy that allow rapid insertion of the needle while maintaining the distance between the needle and plunger.
In view of the foregoing, it is an object of the present invention to provide methods and apparatus for brachytherapy that overcome drawbacks associated with previously-known methods and apparatus.
It is also an object of the present invention to provide methods and apparatus that allow efficient preparation of the apparatus for therapeutic administration.
It is another object to provide methods and apparatus for brachytherapy that require only one medical practitioner.
It is yet another object to provide methods and apparatus that yield easy measurement and maintenance of plunger depth within the needle.
It still further is an object of the present invention to provide methods and apparatus for brachytherapy that allow rapid insertion of the needle while maintaining the distance between the needle and plunger.
These and other objects of the present invention are accomplished by providing methods and apparatus for brachytherapy treatment of prostate cancer comprising a specialized housing that maintains needle/plunger spacing, provides easy measurement of plunger depth within the needle, requires only one practitioner to operate, and enables rapid needle insertion. The plunger is fixed with respect to the housing, while the needle is removably coupled to the housing. Either the plunger or the housing wall is threaded to receive the needle. Measurement indicia on the needle simplify determination of plunger depth within the needle. A locking mechanism maintains plunger depth during needle insertion. To deliver seeds, the needle is rotated while the housing is held stationary, causing the needle to retract along the screw thread.
In a preferred embodiment, the needle is rotated manually. Alternatively, the needle may attach to a swivel that rotates the needle by pulling it proximally along the screw thread. In a still further embodiment, a pull tab may be used to rotate the needle.
Methods of using the present invention are also provided.